JP3185406B2 - Planar antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar antenna used for transmission and reception in a microwave band and a millimeter wave band.

[0002]

2. Description of the Related Art As shown in FIG. 4, a ground conductor 1, a dielectric 2a,
It has a plurality of radiating elements 5 arranged at regular intervals in the vertical and horizontal directions, an antenna circuit board 3 formed with a feed line 6 connected to the radiating elements 5, a dielectric 2b, and a plurality of slots 7 for radio wave radiation. There is known a planar antenna in which the slot plate 4 is overlapped in this order, and the slots 7 are arranged right above the radiating elements 5. Such an antenna
The upper and lower portions of the feed line 6 are electrically shielded by being sandwiched between the ground conductor 1 and the slot plate 4, so that unnecessary radiation from a branch portion or a bent portion of the feed line 6 can be suppressed, and the efficiency can be increased. Things.

In the case of using a linearly polarized wave, this planar antenna connects a feed line to one side of a rectangular radiating element as shown in FIG. 5 (a), or as shown in FIG. 5 (b). A feed line can be connected to the top of the square radiating element.
As shown in (c), a feed line is connected to the edge of the circular radiating element for use. Using such radiating elements, as shown in FIG. 6, the radiating elements 5 are arranged at regular intervals in the vertical and horizontal directions, the excitation directions of the respective radiating elements 5 are matched, and each radiating element 5 is electrically in-phase. Exciting.

[0004]

However, in practice, it is rare that the installation angle of the antenna coincides with the polarization direction of transmission / reception. In such a case, the installation angle of the antenna is changed. It is usual to do so. However, in order to change the installation angle of the antenna, there is a problem that the equipment becomes large and the installation space is wide. Therefore, there is an attempt to change the excitation angle of the radiating element of the antenna.In this case, the arranging angle of each radiating element is changed. The spacing between the radiating elements becomes narrow, and it becomes difficult to provide a feed line. Even if it can be arranged, the distance between the feed line and the radiating element becomes narrow, and the electromagnetic coupling between the feed line and the radiating element cannot maintain the high efficiency characteristic of such a planar antenna. In addition, since power is supplied from the same direction, higher-order mode radiation orthogonal to the polarization direction becomes polarized radiation (cross polarization), and unnecessary radiation occurs in the case of transmission, or in the case of reception. In this case, a problem that the cross polarization ratio is reduced also occurs.

An object of the present invention is to provide a planar antenna which can change the polarization angle of the antenna while maintaining high efficiency.

[0006]

As shown in FIG. 4 , the planar antenna according to the present invention has a ground conductor 1, a dielectric 2a, a plurality of radiating elements 5 arranged at regular intervals in the vertical and horizontal directions, and the radiating elements. An antenna circuit board 3 having a feed line 6 connected to the antenna 5, a dielectric 2 b, and a slot board 4 having a plurality of slots 7 for radio wave radiation are superposed in this order, and each slot 7 is a radiating element. 1, the first radiating element 5a whose excitation direction is disposed at an angle of more than 0 degree and 45 degrees or less with respect to the direction of the array as shown in FIG. And a second radiating element 5b whose excitation direction is arranged at an angle of 180 degrees with respect to the first radiating element 5a is provided adjacent to the first radiating element 5a. On the other hand, when the feed signal of the second radiating element 5b is 180 ° A first sub-array antenna 10 connected to the feed line 6 to be powered with a phase difference, a third radiating element 5c that the driving direction is arranged in the same direction as the first radiating element 5a of the first sub-array antennas 10
The excitation direction is 180 degrees with respect to the third radiating element 5c.
A fourth radiating element 5d arranged at an angle of degrees is provided adjacent to the third radiating element 5c, and the feed signal of the fourth radiating element 5d is shifted by 180 degrees with respect to the feed signal to the third radiating element 5c. A second sub-array antenna 20 to which a feed line 6 is connected so as to be fed with a phase difference;
a and the third radiating element 5c are adjacent to each other, and the second radiating element 5b and the fourth radiating element 5d are adjacent to each other.
The feed line 6 is connected so that the feed signal of the sub-array antenna 20 is fed with a phase difference of 180 degrees.

Further, as shown in FIG. 2, a plurality of such antennas can be formed on the same plane to form a planar antenna having a required gain.

The ground conductor 1 used in the present invention can be a metal plate, an insulating plate with a metal foil bonded thereto, or a metal plated one. An insulating material or air can be used for the dielectric 2a and the dielectric 2b. In the case of the insulating material, it is preferable to use an organic insulating material configured to contain air, such as foamed polyethylene.
When air is used for this dielectric, the antenna circuit board 3
In order to keep the distance between the antenna and the ground conductor 1 or the slot plate 4 constant, an insulating material or a metal spacer can be used at a place where the antenna characteristics are not affected. The antenna circuit board 3 formed with a plurality of radiating elements 5 arranged at regular intervals in the vertical and horizontal directions and a feed line 6 connected to the radiating elements 5 can be made of a material used for a normal wiring board. In addition, the radiating element 5 and the feed line 6 can be formed in the same manner as a method of forming a circuit on a wiring board. That is, a glass cloth-epoxy resin copper-clad laminate, a flexible wiring board base material in which a polyethylene film and a copper foil are bonded together, or the like can be used. Further, the radiation element 5 and the feed line 6 may be formed directly on the insulating material used for the dielectrics 2a and 2b. A slot plate 4 having a plurality of slots 7 for radio wave radiation is provided with the ground conductor 1.
The same can be used.

A first radiating element 5a whose excitation direction is arranged at an angle of more than 0 degrees and 45 degrees or less with respect to the direction of the array;
A feed line 6 is provided so that a signal to be fed is fed with a phase difference of 180 degrees to a second radiating element 5b whose excitation direction is arranged at an angle of 180 degrees with respect to the first radiating element 5a.
To connect each radiating element 5 from the branch point.
The lengths of the feed lines connected to the a and 5b are changed by changing the wavelength of the signal frequency to be used by half the length of the value obtained by integrating the shortening rate in consideration of the permittivity of the dielectrics 2a and 2b. it can. The case where the feed line 6 is connected so that the feed signal of the second sub-array antenna 20 is fed to the first sub-array antenna 10 with a phase difference of 180 degrees can be realized in a similar manner.

[0010]

According to the present invention, as shown in FIG. 1, when the excitation direction is changed, a feed line can be connected to each of the four radiating elements with a short distance, and without increasing the spacing between the radiating elements.
A feed line can be arranged. In addition, the occurrence of the higher-order mode, which is a cause of deterioration of the cross polarization characteristics, can be canceled and suppressed because the feeding directions of the adjacent radiating elements are different by 180.

[0011]

FIG. 2 shows a configuration in which an aluminum plate having a thickness of 1 mm is used as the ground conductor 1 and a slot plate 4 is used as the ground conductor 1.
Using an aluminum plate having a thickness of 0.3 mm, a dielectric 2a,
2b, a polyethylene foam having a thickness of 0.5 mm and a relative dielectric constant of about 1.1 was used.
A copper foil having a thickness of 18 μm was bonded to a polyimide film having a thickness of 25 μm, and unnecessary portions of the copper foil were removed by etching. Radiating elements 5a, b, c, d
Has a length of one side of 0.38 times the free space wavelength at a working frequency of 60 GHz, and a feed line is connected to the apex. The excitation direction was set to 45 degrees with respect to the direction of the arrangement, and the interval between the radiating elements was set to 0.9 times the free space wavelength at a working frequency of 60 GHz. The slot 7 was a square, and the length of one side was 0.6 times the free space wavelength at a working frequency of 60 GHz.
First sub-array antenna 10 thus configured
And four second sub-array antennas 20 formed vertically and horizontally on the same plane. FIG. 3 shows the radiation characteristics of the 16-element array antenna. As a result, as shown in FIG.
A side lobe level of -12 to -14 dB is obtained, the theoretical beam width is 14.2 degrees, and the first side lobe level is almost equal to -13 dB, which is practically usable. there were. Table 1 shows the cross polarization characteristics.
-20 dB over a wide frequency range, as shown in
The following stable characteristics are obtained, compared to the conventional 16-element planar antenna in which the excitation directions are arranged in the same
The improvement was about 10 dB.

[0012]

[Table 1]

As described above, according to the present invention, the excitation direction, that is, the polarization angle can be changed while maintaining high efficiency.

[Brief description of the drawings]

FIG. 1 is a transparent top view showing a main part of an embodiment of the present invention.

FIG. 2 (a) is a perspective top view of one embodiment of the present invention,
(B) is AA sectional drawing of (a).

FIG. 3 is a diagram illustrating characteristics of an antenna according to an embodiment of the present invention.

FIG. 4 is a schematic perspective view showing a conventional example.

FIGS. 5A to 5C are top views each showing a shape of a partial radiating element of a conventional example.

FIG. 6 is a perspective top view showing a main part of a conventional example.

FIG. 7 is a transparent top view showing another conventional example.

[Explanation of symbols]

 1. Ground conductor 2a, 2b. Dielectric 3. Antenna circuit board 4. Slot plate 5. Radiating element 6. Feeding line 7. Slot 10. First sub-array antenna 20. Second sub-array antenna

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01Q 3/00-3/46 H01Q 21/00-21/30 H01Q 23/00 H01Q 25/00-25 / 04

Claims (1)

(57) [Claims] 1. An antenna circuit board 3 having a ground conductor 1, a dielectric 2a, a plurality of radiating elements 5 arranged at regular intervals in the vertical and horizontal directions, and a feed line 6 connected to the radiating elements 5.
In a planar antenna in which a dielectric 2b and a slot plate 4 having a plurality of slots 7 for radio wave radiation are superposed in this order, and each slot 7 is arranged directly above each radiating element 5, the excitation direction is A first radiating element 5a arranged at an angle of more than 0 degree and 45 degrees or less with respect to the direction of the arrangement, and a second radiating element arranged at an angle of 180 degrees with respect to the first radiating element 5a, And a feed line such that the feed signal of the second radiating element 5b is fed with a phase difference of 180 degrees with respect to the feed signal of the first radiating element 5a. 6 and a third sub-array antenna 10 whose excitation direction is arranged in the same direction as the first radiating element 5a of the first sub-array antenna 10.
Radiating element 5c and the third radiating element 5c
Fourth radiating element 5 arranged at an angle of 180 degrees with respect to
d are provided adjacent to each other, and the feed signal of the fourth radiating element 5d is 1 with respect to the feed signal of the third radiating element 5c.
A second sub-array antenna 20 connected to the feed line 6 so as to be fed with a phase difference of 80 degrees, the first radiating element 5a and the third radiating element 5c being adjacent to each other, and The radiating element 5b and the fourth radiating element 5d are arranged adjacent to each other, and the first sub-array antenna 1
A flat antenna, wherein a feed line 6 is connected so that a feed signal of the second sub-array antenna 20 is fed with a phase difference of 180 degrees with respect to 0.